When your head hits the pillow, your eyes still function. "But they can only sense light versus dark," says physician Michael Breus, a clinical psychologist who founded SoundSleepSolutions.com, a sleep-information Web site. This explains why a bright light or the sunrise often wakes a person up.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.